Electronic control unit for a motor vehicle and motor vehicle

Abstract

Electronic control unit (10) for a motor vehicle (1), comprising: - at least two circuit boards (18, 19) which are coupled to one another and have a plurality of electronic elements (21) and a plurality of thermal connection elements (13), - a housing (11, 12) which encloses the printed circuit boards (18, 19) in a predetermined manner, - at least one air outlet opening (14) formed on and penetrating a side wall of the housing (11, 12), and - a fan unit (15) which is coupled to the housing (11, 12) and is designed to provide a predetermined air flow for cooling the electronic control unit (10), wherein the positions of the electronic elements (21), the thermal connection elements (13), the at least one air outlet opening (14) and the fan unit (15) are predetermined in a coordinated manner so that a diagonal air flow can be set up within the housing (11, 12) along a main extension plane of the printed circuit boards (18, 19).

Description

[0001] The present invention relates to an electronic control unit for a motor vehicle and a motor vehicle with such a control unit.

[0002] Motor vehicles contain numerous electronic components that generate heat during operation, which is typically dissipated to cool these components. Electronic cooling is based on the physical principles of heat conduction, convection, and / or electromagnetic radiation. A distinction is also made between active cooling and passive cooling.

[0003] The document DE 10 2018 221 420 A1 relates to a control unit for evaluating signals for a vehicle. The document DE 10 2019 129 427 A1 relates to a housing for a control unit of a motor vehicle. The document DE 103 49 573 A1 relates to a housing arrangement for electronic devices for mounting on vehicles. The document DE 38 37 206 A1 relates to an electrical switching device for motor vehicles. The document DE 10 2013 017 215 A1 relates to an electronics housing. The document DE 10 2008 033 193 A1 relates to an engine control device of a vehicle.

[0004] It is an object underlying the invention to provide a cooling system for electronic components which contributes to a long-lasting and reliable operation of these components.

[0005] The problem is solved by the features of the independent patent claim. Advantageous further developments are specified in the dependent patent claims.

[0006] According to one aspect of the invention, an electronic control unit for a motor vehicle comprises at least two circuit boards that are coupled to one another and have a plurality of electronic elements and a plurality of thermal connection elements. The control unit further comprises a housing that predefinedly encloses the circuit boards. Furthermore, at least one air outlet opening is provided, which is formed on and penetrates a side wall of the housing. The control unit further comprises a fan unit that is coupled to the housing and is configured to provide a predefined air flow for cooling the control unit.The positions of the electronic elements, the thermal connection elements, the at least one air outlet opening and the fan unit are designed to be coordinated with one another so that a predominantly diagonal air flow can be set up within the housing along a main extension plane of the printed circuit boards.

[0007] The described design of the electronic control unit enables temperature management that provides efficient and reliable cooling even at relatively high power and power density. As an electronic component, the control unit implements, for example, a cockpit computer system for the motor vehicle, which can receive, process, and transmit signals. The control unit can also be referred to as the motor vehicle's on-board computer.

[0008] The fan unit, for example, is designed as an intake fan and is positioned specifically in the area of ​​electronic components that generate particularly high levels of heat during operation and therefore require preferential cooling. For example, the fan unit is positioned underneath electronic components with the highest heat dissipation.

[0009] According to a further development of the control unit, the housing comprises an upper housing section and a lower housing section, wherein the upper housing section is formed from a die-cast aluminum and / or the lower housing section is formed from sheet steel. Furthermore, the upper and / or lower housing sections can have an anodized and / or painted surface. This can contribute to even more reliable heat dissipation and even more efficient cooling of the control unit.

[0010] The circuit boards are, in particular, rectangular in shape and have a significantly greater length and width compared to a relatively small thickness. Thus, their respective main extension plane is defined by the length and width. Accordingly, the housing is preferably cuboid-shaped and surrounds the internal circuit boards from above and below. In the context of this description, terms such as "top," "bottom," "front," "rear," and "side" refer to positions or orientations of elements as they are typically found in an operational state of the control unit installed in a motor vehicle.

[0011] According to a further development of the control unit, at least a number of the thermal connection elements are designed in coordination with the surrounding housing such that they penetrate a respective wall of the housing in a predetermined manner. The thermal connection elements are, for example, special designs of a sheet metal part or a die-cast part and are configured as deep drawings.

[0012] The thermal connection elements are located, for example, as pot- or funnel-shaped components in specifically designated positions, which are intended in particular to create a long air flow path and contribute to efficient cooling of the control unit.

[0013] According to a further development, the control unit has one or more partition walls arranged between the housing and one of the circuit boards or between the circuit boards, wherein a respective position of the respective partition wall is predetermined in coordination with the positions of the thermal connection elements, the at least one air outlet opening, and the fan unit. The partition walls are arranged in particular on an upper side of a main circuit board, which is realized by one of the circuit boards.

[0014] According to a further development, the at least one air outlet opening is provided by an air outlet grille. The air outlet grille has a plurality of openings and can also be referred to as a perforated grille, and is designed in particular to match the ventilation performance of the fan unit and the geometry of the housing. For example, the housing is configured to have a volume of 0.8 - 1.0 dm 3 encloses, so it is useful to design the air outlet grille so that it has an area of ​​1400-1700 mm 2 through the air outlet grille. The specified area refers to the total area, which includes the area of ​​the grille and the areas of the openings defined by the grille. For example, the air-permeable openings represent a share of 30%-50% of the total area.

[0015] According to a further development of the control unit, the at least two circuit boards are arranged one above the other with respect to their main extension directions and each have a plurality of thermal connection elements that are directed away from the other circuit board or outward and extend through a wall of the upper housing section or a wall of the lower housing section. Alternatively, the control unit can have three or more circuit boards that are arranged one above the other with respect to their main extension directions.

[0016] According to a further development of the control unit, the electronic elements and / or the thermal connection elements are coupled to the circuit board(s) and / or the housing using a thermally conductive material with a thermal conductivity of 4-10 W / mK. This allows for particularly reliable heat transfer or heat dissipation. Alternatively, other value ranges for the thermal conductivity of a thermally conductive material are also possible.

[0017] According to a further aspect of the invention, a motor vehicle comprises an embodiment of the electronic control unit, which is arranged in the motor vehicle and, for example, implements an on-board computer of the motor vehicle. Because the motor vehicle comprises one of the previously described embodiments of the control unit, the properties and features described in connection with the control unit are also disclosed for the motor vehicle, and vice versa.

[0018] It is a finding related to the invention that any system can theoretically be cooled to a required temperature, but not necessarily with the required power level, global and local power density, limited installation space, structural mechanical, electrical, manufacturing, or other restrictions. The described design of the control unit enables a temperature management system with a cooling-optimized architecture.

[0019] Regulatory requirements require different, protected and separate areas, for example on the top side of a circuit board, which, for example, implements a main circuit board as a printed circuit assembly. Airflow through forced convection for cooling is therefore very limited. For reasons of electromagnetic compatibility of the installed electronic components, the gaps between the top and bottom of the main PCB are closed by the housing, preventing air exchange. Furthermore, the system consists of three circuit boards, whose different energy densities must be taken into account, and there is no space for a PCB fan cutout. If the control unit forms a system with relatively high power loss (radiated power), this can be reliably dissipated thanks to the described design. The control unit can therefore meet complex requirements combined with high cooling performance.

[0020] It is a finding in connection with the invention that high power dissipation combined with high power density under restrictions requires reliable cooling of all electrical components below their maximum permissible temperature specifications in order to ensure safe and trouble-free, or at least low-trouble operation. Accordingly, the control unit and its design are analyzed to define suitable cooling measures for all installed electrical components. While meeting specified restrictions, component temperatures can be kept low. Since both temperature-critical electrical components and high-power density components can be distributed across printed circuit boards, the described embodiments of the control unit enable holistic, reliable system cooling.

[0021] The control unit's temperature behavior was analyzed in detail using thermal simulation. By combining analysis options in the form of variants, parameter studies, and optimization calculations, a suitable cooling solution can be found for each individual component of the control unit and / or for the control unit as a whole. This consists, for example, of various individual measures and holistic measures: targeted, individual connection of electrical components to the housing, with and without thermal interface material (TIM), selection of thermal paste with high thermal conductivity as TIMs, optimization of fan position and flow behavior, and optimization of the perforated grid through targeted design measures. In particular, active cooling of the underside of the motherboard is provided, which is unobstructed by, for example, bulkheads.

[0022] The housing is preferably constructed from two halves, with a die-cast aluminum housing forming the upper half on or above the top side of the upper circuit board. This allows for the connection of high-performance components to the main circuit board. Furthermore, active cooling of the broadcast and video PCBs can be implemented using the airflow from flow optimization, as well as cooling by connecting components to the bottom of the housing using TIMs.

[0023] The control unit, for example, implements a system with 8-10 W power dissipation for individual components and 45-60 W system power dissipation. The housing comprises an anodized and / or painted die-cast aluminum upper section and a sheet steel lower section for a system with a volume of 0.8 - 1.0 dm 3The circuit boards comprise a main CPU, critical memory chips, and other electronic components and modules with high power output and / or critical temperature specifications on a circuit board that forms the main board and to which these components are thermally connected. The advantageous use of TIM for connection preferably meets the requirement of a thermal conductivity of 4-10 W / mK.

[0024] Furthermore, the control unit can have additional circuit boards. Preferably, when the control unit is in operation, the underside of the lowest circuit board and / or the existing circuit boards in the system is cooled by the air flow provided by the fan unit. For the best possible cooling performance, the air flow is subject to the requirement to flow through the system for as long as possible. Therefore, the fan unit is preferably positioned underneath the components with the highest heat dissipation. The air is preferably discharged through a perforated grille at the greatest possible diagonal distance from the fan unit, with the perforated grille or the surface having a value of 1400 - 1700 mm in relation to the previously described volume of the housing. 2A flow area that is too small reduces the airflow, while one that is too large does not direct the airflow optimally. The specified area refers to the total area where the openings in the perforated grille provide an air-permeable surface that occupies approximately 30%-50% of the total area.

[0025] The approach presented here clearly defines constraints, objectives, and degrees of freedom, enabling targeted and efficient solution finding without prototypes by analyzing a multitude of variants, parameter studies, and optimization calculations based on fluid dynamics using computer-aided simulations (CFD) in a highly complex requirements environment. The best possible combination and application of available technical and economic cooling solutions lead to the described architectures according to the control unit embodiments.

[0026] The control unit and analog electronic systems are suitable for applications in high-performance computing, among others. The implementation of the control unit architecture is particularly scalable and adaptable to technical requirements and economic constraints, making it suitable for electronic systems using liquid cooling, heat pipes, or Peltier elements, for example. Furthermore, the use of other materials is also possible, which can contribute to further improvements in heat dissipation.

[0027] The following illustrates exemplary embodiments of the described arrangement using schematic drawings. They show: Fig. 1 a schematic embodiment of a motor vehicle with a control unit, and Fig. 2-5 an embodiment of the control unit in different views.

[0028] Fig. 1 shows a schematic representation of a motor vehicle 1 with an electronic control unit 10 that is integrated or arranged in the motor vehicle 1. With respect to a vehicle longitudinal axis L and the illustrated view, the control unit 10 has a front side 2 and a rear side 3. With reference to the further Fig. 2-5, the control unit 10 further comprises a top side 4 and a bottom side 5. A side wall or outer side of the control unit 10 is accordingly located between the top side 4 and the bottom side 5.

[0029] In the context of this description, terms such as “top”, “bottom”, “front”, “back” and “side” refer to positions or orientations of elements as they appear in the Fig. 1 to 5 and as they are usual in an operational state of the control unit 10 installed in the motor vehicle 1.

[0030] The Fig. 2-5 show in various perspective views an embodiment of the control unit 10, which due to its specific structure and the targeted arrangement of the interacting elements enables a particularly efficient dissipation of heat in an operation.

[0031] Fig. 2 shows a perspective view of the control unit 10 from above, looking at the top 4 and the back 3. Fig. 3 shows a perspective view of the control unit 10 from below, looking at the bottom 5 and the back 3. Fig. 4 shows a perspective view of the control unit 10 without housing 11, 12, 20 from an angle above, looking at the top 4 and the back 3. Fig. 5 shows a perspective view of the control unit 10 without housing 11, 12, 20 from below, looking at the bottom 5 and the back 3.

[0032] The electronic control unit 10 comprises at least two rectangular printed circuit boards 18, 19 which are coupled to one another and have a plurality of electronic elements 21 and a plurality of thermal connection elements 13 (see Fig. 4 and Fig. 5). Preferably, the electronic control unit 10 comprises three circuit boards, so that, for example, the circuit board 19 forms a two-part circuit board or has two circuit boards. The following primarily focuses on the design of the control unit 10 with two circuit boards 18 and 19, although corresponding properties and features are also transferable to a design with three or more circuit boards.

[0033] The upper circuit board 18 can also be referred to as the main circuit board or main circuit board. The lower circuit board 19 is arranged at a predetermined distance from the upper circuit board 18, so that the circuit boards 18, 19 are arranged one above the other with respect to their respective main extension planes. The lower circuit board 19 can also be implemented as a two-part circuit board or comprise two circuit boards, so that the control unit 10 has a total of three circuit boards.

[0034] The control unit 10 further comprises a cuboid-shaped housing with an upper housing section 11 and a lower housing section 12, which pre-enclose the circuit boards 18, 19. In addition, a front housing section 20 can be provided on the front side 2, which pre-covers the front side 2 of the control unit 10 and is coupled to the circuit boards 18, 19. The upper housing section 11 is made, for example, from a die-cast aluminum and anodized and / or painted. The lower housing section 12 is formed, for example, from sheet steel. The housing 11, 12, 20 is designed, for example, to have a volume of 0.8 - 1.0 dm 3 encloses.

[0035] The control unit 10 also comprises an air outlet opening in the form of an air outlet grille 14, which is arranged between the two circuit boards 18, 19 and integrated in a side wall of the lower housing section 12 (see Fig. 3 and Fig. 5).

[0036] The air outlet grille 14, for example, provides an air-permeable area of ​​1400-1700 mm 2 ready.

[0037] The control unit 10 further comprises a fan unit 15, which is coupled to the housing 11, 12 and / or the circuit boards 18, 19. The fan unit 15 is designed, for example, as an intake fan and is configured to provide a predetermined air flow for cooling the control unit 10.

[0038] The control unit 10 also comprises a plurality of bulkheads 17 arranged at predetermined positions on the upper circuit board 18 (see Fig. 4). Alternatively or additionally, bulkheads 17 can be arranged on the lower circuit board 19. The bulkheads 17 are arranged between the upper housing section 11 and the upper circuit board 18 and are coordinated with the positions of the other elements. The bulkheads 17 serve to prevent the spread of fire in the event of a flame forming in a circuit board area.

[0039] The positions of the electronic elements 21, the thermal connection elements 13, the air outlet grille 14, the partition walls 17 and the fan unit 15 are coordinated with one another, so that during operation of the control unit 10, a predominantly diagonal air flow is established within the housing 11, 12, 20 along the main extension planes of the printed circuit boards 18, 19. Fig. 3, such a diagonal air flow direction 16 is illustrated with a bold arrow.

[0040] The airflow within the housing 11, 12, 20 preferably follows the longest possible path to enable reliable cooling of the electronic components. Furthermore, the fan unit 15 and the air outlet grille 14 are located at opposite corners of the control unit 10 to further contribute to effective heat dissipation.

[0041] The pot-shaped or funnel-shaped thermal connection elements 13, some of which are formed on the upper side of the upper circuit board 18 and others on the underside of the lower circuit board 19 (see Fig. 4 and Fig. 5) are positioned and designed accordingly. The thermal connection elements 13 are formed, for example, in a cast or formed in a sheet metal by deep drawing and contribute to flow guidance and heat dissipation.

[0042] The described design of the electronic control unit 10 enables temperature management that provides efficient and reliable cooling even at relatively high power and power density. The control unit 10, as an electronic component, implements, for example, a cockpit computer system or an on-board computer for the motor vehicle 1, which can receive, process, and transmit signals. List of reference symbols 1 motor vehicle 2 Front of the control unit 3 Back of the control unit 4 Top of the control unit 5 Bottom of the control unit 10 Control unit of the motor vehicle 11 upper housing section of the control unit 12 lower housing section of the control unit 13 thermal connection element of the housing section 14 air outlet grilles 15 intake fans 16 Air flow direction 17 bulkhead 18 first circuit board 19 second circuit board 20 front housing section 21 electronic element L Longitudinal axis of the motor vehicle

Claims

[1] Electronic control unit (10) for a motor vehicle (1), comprising: - at least two circuit boards (18, 19) which are coupled to one another and have a plurality of electronic elements (21) and a plurality of thermal connection elements (13), - a housing (11, 12) which encloses the printed circuit boards (18, 19) in a predetermined manner, - at least one air outlet opening (14) formed on and penetrating a side wall of the housing (11, 12), and - a fan unit (15) which is coupled to the housing (11, 12) and is designed to provide a predetermined air flow for cooling the electronic control unit (10), wherein the positions of the electronic elements (21), the thermal connection elements (13), the at least one air outlet opening (14) and the fan unit (15) are predetermined in a coordinated manner so that a diagonal air flow can be set up within the housing (11, 12) along a main extension plane of the printed circuit boards (18, 19). [2] Electronic control unit (10) according to claim 1, wherein the housing comprises an upper housing section (11) and a lower housing section (12), wherein the upper housing section (11) is formed from an aluminum die-cast and / or the lower housing section (12) is formed from sheet steel. [3] Electronic control unit (10) according to claim 2, wherein the upper and / or lower housing section (11, 12) has an anodized and / or painted surface. [4] Electronic control unit (10) according to one of the preceding claims, in which at least a number of the thermal connection elements (13) are designed in coordination with the housing (11, 12) surrounding them, so that the number of thermal connection elements (13) is cast or deep-drawn in a predetermined manner with a respective wall of the housing (11, 12). [5] Electronic control unit (10) according to one of the preceding claims, wherein the at least one air outlet opening (14) is provided by an air outlet grille (14). [6] Electronic control unit (10) according to claim 5, wherein the housing (11, 12) has a volume of 0.8 - 1.0 dm 3 and the air outlet grille (14) has an area of ​​1400-1700 mm 2 provides. [7] Electronic control unit (10) according to claim 2 or one of claims 3 to 6 when referring back to claim 2, in which two printed circuit boards (18, 19) are arranged one above the other with respect to their main directions of extension and each have a plurality of thermal connection elements (13) which are directed away from the respective other printed circuit board (18, 19) and are designed as a section of a wall of the upper housing section (11) or a wall of the lower housing section (12) of the housing, or electronic control unit (10) according to claim 1 or one of claims 4 to 6, if not referring back to claim 2 or 3, in which two printed circuit boards (18, 19) are arranged one above the other with respect to their main directions of extension and each have a plurality of thermal connection elements (13) which are directed away from the respective other printed circuit board (18,19) and are designed as a section of a wall of an upper housing section (11) or a wall of a lower housing section (12) of the housing., [8] Electronic control unit (10) according to one of the preceding claims, in which the electronic elements (21) and / or the thermal connection elements (13) are coupled to electrical components of one or both circuit boards (18, 19) and / or the housing (11, 12) by means of a thermally conductive material having a thermal conductivity of 4-10 W / mK. [9] Motor vehicle (1), comprising: an electronic control unit (10) according to one of the preceding claims, which is arranged in the motor vehicle (1).

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